The Biology Book: From the Origin of Life to Epigenetics, 250 Milestones in the History of Biology (2015)

Blood Cells

Blood has played a central role in the lives of ancient people, appearing in their religious beliefs, myths, health, and as a symbol of courage and sacrifice. Across many cultures, and surviving to this day, is the belief that blood is a symbol of family relationships, as well as a tribal and natural bond. For the ancient Greeks, blood was the essential nutrient of life, the center of life itself, the soul, and death was, by contrast, final and irrevocable, when blood was lacking. The exceptions were the immortal gods and demons, who were without blood but not dead. The Greeks did not commonly engage in blood sacrifices, unlike some other cultures, such as the Anglo-Saxons and Norsemen, who deemed that blood transferred the power of its source.

The importance of blood extends to other cultures and periods. The Judaic and Islamic scriptures forbid the consumption of blood, while some Christian churches view wine as the symbol of the blood of Jesus. When a man has a nosebleed in some East Asian cultures, it is a sign of sexual desire, and the Japanese have classified personality traits on the basis of blood types. The Gothic novelist Bram Stoker might have been inspired by the New World vampire bat, which feeds exclusively on blood, when he created his eponymous character in the 1897 novel Dracula.

Scientists have studied how blood transports nutrients and oxygen to cells and carries waste materials from the cells for ultimate disposal from the body. Jan Swammerdam, a Dutch biologist, was the first to see red blood cells under a microscope in 1658. Antonie van Leeuwenhoek described their size and shape and illustrated them in 1695. Around 1840, the French professor of medicine Gabriel Andral described white blood cells and was a pioneer in blood chemistry and scientific hematology, which integrated clinical and analytical medicine. Several years later, the French physician Alfred Donné observed the first blood platelet. Lastly, Paul Ehrlich’s wide-ranging scientific accomplishments include an 1879 staining technique for differential counting of white blood cells.